/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1991, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <err.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

char *getbsize(int *headerlenp, long *blocksizep) {
  static char header[20];
  long n, max, mul, blocksize;
  char *ep, *p;
  const char *form;

#define KB (1024L)
#define MB (1024L * 1024L)
#define GB (1024L * 1024L * 1024L)
#define MAXB GB /* No tera, peta, nor exa. */
  form = "";
  if ((p = getenv("BLOCKSIZE")) != NULL && *p != '\0') {
    if ((n = strtol(p, &ep, 10)) < 0)
      goto underflow;
    if (n == 0)
      n = 1;
    if (*ep && ep[1])
      goto fmterr;
    switch (*ep) {
    case 'G':
    case 'g':
      form = "G";
      max = MAXB / GB;
      mul = GB;
      break;
    case 'K':
    case 'k':
      form = "K";
      max = MAXB / KB;
      mul = KB;
      break;
    case 'M':
    case 'm':
      form = "M";
      max = MAXB / MB;
      mul = MB;
      break;
    case '\0':
      max = MAXB;
      mul = 1;
      break;
    default:
    fmterr:
      warnx("%s: unknown blocksize", p);
      n = 512;
      max = MAXB;
      mul = 1;
      break;
    }
    if (n > max) {
      warnx("maximum blocksize is %ldG", MAXB / GB);
      n = max;
    }
    if ((blocksize = n * mul) < 512) {
    underflow:
      warnx("minimum blocksize is 512");
      form = "";
      blocksize = n = 512;
    }
  } else
    blocksize = n = 512;

  (void)snprintf(header, sizeof(header), "%ld%s-blocks", n, form);
  *headerlenp = strlen(header);
  *blocksizep = blocksize;
  return (header);
}
